Sector caveat
Use a 5-year average of FCF, not trailing twelve months. Single-year FCF for an industrial is closer to noise than signal.
Estimating maintenance CapEx
Damodaran's practitioner heuristic[Damodaran]: set maintenance equal to D&A for a steady-state firm, then adjust for inflation in equipment prices. Alternatively, isolate a flat-unit-volume year and take that year's CapEx as the maintenance baseline.
Working-capital seasonality
Heavy-equipment makers carry inventory builds ahead of the spring sales season. Receivables peak after Q4 dealer-channel orders. The Q1 cash flow statement is nearly always the worst-looking quarter, irrespective of trailing twelve-month health.